This invention relates generally to improved electronic switches, and specifically to those incorporating capacitive sensing technology, and to the manner in which an activation or operation event is defined.
In recent years, electronic products have increasingly incorporated intelligent switches to realize more functionality than a simple on/off action. One area where this is especially evident is in portable lighting products, such as headlamps, key-ring lights and torches, although certainly not limited to this field only. Due to inventions such as that contained in U.S. Pat. No. 6,249,089 to Bruwer, more and more products now have features previously only realizable with a more complex user interface. However, a large number of these implementations still make use of mechanical structures to make or break current, be it push buttons, tactile dome switches or large pole type structures. Such mechanical switches may suffer from a number of drawbacks. They can be prone to wear and tear. It can be costly to manufacture them in a robust/rugged manner which is immune to harsh environment use. To realize a waterproof product may require a dedicated flexible membrane over the mechanical switch, with all the associated challenges and cost implications.
Capacitive sensing technology has also increased in prevalence recently. One of the more evident fields of deployment is in mobile telephones and laptop computers. However, inherent to the technology is the possibility of inadvertent activation. This, coupled with the universal user requirement of haptic feedback on switch location, has possibly kept capacitive switches out of a large number of possible applications, notably the above mentioned fields of portable lighting and automotive controls. Only placing a typical capacitive sensing switch in a recess does not solve the problem of inadvertent activation satisfactorily. A user's clothing, or other dielectric objects, might penetrate the recess and activate the switch.
The invention disclosed hereafter purports to overcome the drawback of inadvertent activation, thereby allowing use of capacitive switching technology in fields heretofore unattractive for some reason, and to overcome some of the drawbacks of mechanical switches.